Mavic Pro 2 lost at sea - what could I have done differently

[Deleted member 114292]

The problem with ignoring wind warnings is that their binary it’s like the oil light in your car oil light comes on you don’t know if you’re 1 quart down or 4 quarts down.
So you ignore it for a while and you get away with it until you don’t.
I’ve driven this car with the oil light on for a week and now the engines froze up and I don’t understand why. I’ve done it before Many times.

 

[E90RAW]

The aircraft was making progress at 31 m altitude, but it was struggling to hold a course to get to the home point.

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On the other hand, it did have enough battery reserve to make it to land.

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Unfortunately that track intersects the headland that is higher than the RTH height of 30 m. Since RTH obstacle avoidance was not enabled, the flight will likely have ended just short of the yellow pin below, taking into account vegetation height. Note, however, that the winds were quite variable, and so there is significant potential error in that location estimate. Whjat might be worthwhile is to search the 30 m contour on that headland.

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Well, as usual a great and informative session. Unfortunately we are all learning from others mistakes (as well as our own) but the best lessons in life are from mistakes, not from hitting the lottery.

 

[E90RAW]

Yup, a clear blow away... with several pilot mistakes done once the drifting were noticed due to lacking knowledge about his equipment and the circumstances he decided to fly in.

Below the event in a couple of points (instead of a colorful chart ) ... have colored the disastrous actions in red & the good/or better ones in green.


-Mainly you started to drift out sideways with the wind at the time you switched over to Cinematic mode, at 39sec.

-From here at 78m height you did put in full positive throttle (as stick mode 3 meaning elevator) but without rotating the AC back towards the HP.

-At 75sec you also add in full positive elevator (as stick mode 3 meaning throttle) and ascend up to 195m height making the winds even stronger, still drifting sideways not heading HP.

-At 115sec you for the first time direct the AC back towards the HP ...still on 195m height.

-Shortly after, you get it ... now with the AC directed towards the HP you nail the sticks for descending & full speed forward, but still drifting out to sea.

... All above still remaining in Cinematic mode which only seems to gives max 15 degrees pitch angle ... instead of switching over to Sport and made 35 degrees possible.

-Then shortly after at 159sec you give up & goes for RTH ... then at 148m height. This makes it possible for the AC to use a 25 degree pitch angle & the drift speed goes from approx 8m/s down to 2,5m/s

-During the RTH phase you continued to apply negative elevator (as stick mode 3 meaning throttle) in periods ending up on 102m height when you get disconnected for the first time.

-You seems then to continue applying negative elevator (as stick mode 3 meaning throttle) during the video/log stream disconnect but were probably still in control of the AC as it is on 33m height when the video/log stream continues. You are now also making way towards the HP

- But short after you lost connection for good ... the battery were then down to 59% with 1517m to go to reach the HP & a coming land battery level of 10%. The heading speed then were roughly 2-3m/s in the right direction & the log reports 674sec useful battery time left (not sure if it's to auto landing or to 0%) meaning in best case 674sec of flight with 3m/s still left in straight line to HP (and nearly half of that remaining distance to HP consisted of ground). But I leave that judgement to @sar104, he's the best of those kind of estimations.

Thank you all for the time you put into this. Great lessons for all.

 

[E90RAW]

Hi

I lost my drone (Mavic 2). I’m happy to assume I’ve made a bunch of mistakes - sure there are loads to find! DJI is looking at the logs. What I’d to understand is:

(A) what happened to the drone after I lost connection and

(B) what could I have done differently.


It was a windy day but it is always windy here and if I never flew the drone with a wind warning I’d almost never fly it. I get them all the time and have had no issues before.

My plan was to send it out, check it was ok in the wind and then keep going if it was ok. It took me a while to realize it was drifting in the wind - and at first assumed it was set to FPV mode which is why camera was titled (it wasn’t). I also turned it to cinematic mode which looking back may have made the drift much worse (?)

When I realized what was happening eg the wind was pushing the drone out, I tried to bring it lower but probably took too long to do that. I also tried to manouver it behind one of the two headlands but it seemed a bit futile until it got much lower. When it wasn’t making any real headway I panicked and put into RTH mode and with the lower altitude it was making decent headway with about 70% battery and only around 800m to make it to land (not the home point - the land on the headland - would have switched off RTH when it go adjacent to the land and steered it over).

But the connection dropped out while it was over a km away. I moved around the beach to try and open up the signal but the connection never came back. My assumption is the drone has crashed into the water but I don’t know how or why exactly. If it is not making headway due to wind does it just land even if over water?

I’m clutching at straws here but assuming could identify an approximate position, what are chances it could be found on sea floor (assuming the water is shallow enough to dive). Drone is so light my assumption is that when it hits the water it would deviate a bit with any current until it hits the bottom. Does this mean that even if I could identify a pretty good search area there is almost no chance of finding it on the ocean floor? Reason I ask is I have Refresh. A few questions


1. Did putting it into cinematic mode make the control much worse?

2. If I had been able to switch to sports mode before I lost signal would it have made it back? Winds were coming and going but at one stage it was travelling well even with wind gusts against it.

3. Did I need to have switched off auto land over water? Read that they can just land if they are getting stuck

4. What would have happened in this scenario eg after I lost signal where did the drone go/what did it do?

5. Is it strange that it lost signal and wasn’t able to land when it had so much battery left? Did something happen to drone which affected the connection?

6. Any ideas where it would have landed...? How quick do they sink...?



Thanks

Thanks for sharing

 

[Cymruflyer]

Well, as usual a great and informative session. Unfortunately we are all learning from others mistakes (as well as our own) but the best lessons in life are from mistakes, not from hitting the lottery.

I'd still prefer to hit the lottery!

 

[dkuhne]

The intention with the color markings & this time skip the chart (which many doesn't grasp if not explained) was just that ... think the answers to at least question 1-4 is in the red but point taken.

for the record, i have zero knowledge on this subject, and found your green/red approach perfect to understand.

 

[Dale D]

I have tired to work my way through all of the above posts. I must admit it is way too much for my brain. The bottom line I got out of the threads was...Do not fly in strong winds. I know that it is impossible to avoid winds near the ocean. I save my flying for calm areas or I just do not fly because I am just not that good of a pilot. I have never been in Sport Mode. To me, Sport mode means risk.Not interested in speed and hope to never need sport mode for recovering my drone.

 

[Ralph thompson]

Notwithstanding all the positive reinforcement above, you were flying your drone at more than twice the maximum operating wind speed limit specified by DJI. (10mps or 22 miles per hr). In Canada this would be illegal and insurance if you had it would be invalid. Manufacturers have technical reasons for specifying operating limits. Structural limits are probably 2 or 3 times the operating limit but this allows for spikes and some wiggle room. Off shore winds are notoriously gusty, you may well have experienced a structural failure. Unless you‘re wealthy & can afford to keep buying drones, I suggest first to read the manual, take some lessons from an approved instructor where they’ll help u with developing a preflight checklist.

 

[E90RAW]

I have tired to work my way through all of the above posts. I must admit it is way too much for my brain. The bottom line I got out of the threads was...Do not fly in strong winds. I know that it is impossible to avoid winds near the ocean. I save my flying for calm areas or I just do not fly because I am just not that good of a pilot. I have never been in Sport Mode. To me, Sport mode means risk.Not interested in speed and hope to never need sport mode for recovering my drone.

The lessons I get :
1). Know the weather conditions ahead of time.
2). Do a test flight into the wind, and its always better to go into the wind first and return home with wind in the sails (as an avid cyclist thats my favorite rule).
3). Most of the problems/crashes with the drones are operator error. That's comforting.
4). Sport mode is the BEST. It's a lot of fun, and it can get you out of a jam.

 

[acrossthenight]

I went back the town today where I lost it and checked out the area suggested by @sar104. It was a pretty steep, slippery and difficult chunk of hillside to try and look around. I spent 4 hrs sliding around and climbing through thick brush trying to stick around 25-32 m (to account for trees) but no love. There is a large drop-off
about 20ft from the gps coords and in that wind it feels like there is a good chance it drifted into a high rock wall and dropped into the water.
It was such a hard to get to
place And so difficult to get around I doubt anyone had picked it up before I got there. An offering for the drone gods. Thanks for the pointers. I had a decent adventure trying to find it anyway.

 

[Steve L Reid]

If you never want to lose your DJI over water never fly over water!

 

[GadgetGuy]

If you never want to lose your DJI over water never fly over water!

Corollary: If you never want to risk losing your drone, never fly it!
It's called assumption of the the risk. Good piloting minimizes the risk, but it is never zero!

 

[Drones.n.Pixels]

Thanks for your to the point responses. Does this mean if right away I had flicked it to sports mode I might still have a drone...?

If you are experienced pilot (or quite talented), yes. Otherwise, hitting RTH and not interfering with it is best bet. Loss of signal with RC is not the problem, wind on the other hand yes.

Assuming this is fairly accurate. The winds were quite high and blowing out to sea....

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With head wind of 35m/ph, which is not much less than speed of Mavic, I don't think you would have made it to the shore. Sport mode would have helped, but i don’t think this would be enough to get you out of water. Activation of RTH earlier would’ve probably help a bit, but with strong wind towards the sea it was risky to fly alltogether.

 

[steve_lyt]

you could have set RTH on loss of signal. that may have saved your drone. and I usually do a hover test , before I start flying. I just hover 5 or 6 foot and see if it stays stable , then at 10m approx. this works for me. and wind of that strength should be avoided

 

[Meta4]

you could have set RTH on loss of signal. that may have saved your drone.

Unless you change from the default setting, any DJI drone will automatically RTH on loss of signal.
Almost nobody changes that default and the OP's LoS action was set to RTH.
His Mavic would have initiated RTH when he finally lost signal because the drone was flown behind an obstruction.
But his RTH height was not sufficient to clear the headland as the drone got closer.

His RTH height was set at 100 ft but RTH could only make any headway once he descended below 100 ft.
Having RTH initiate earlier in the flight while he was well above 100 ft would have only left the drone to be blown further out to sea.

 

[GadgetGuy]

Unless you change from the default setting, any DJI drone will automatically RTH on loss of signal.
Almost nobody changes that default and the OP's LoS action was set to RTH.
His Mavic would have initiated RTH when he finally lost signal because the drone was flown behind an obstruction.
But his RTH height was not sufficient to clear the headland as the drone got closer.

His RTH height was set at 100 ft but RTH could only make any headway once he descended below 100 ft.
Having RTH initiate earlier in the flight while he was well above 100 ft would have only left the drone to be blown further out to sea.

Good insight into a bad situation. Been there, done that, and had to ditch land on what turned out to be a Navy Base on a holiday, back in the early days. Nice lady Lieutenant Commander on duty helped me retrieve it! Lessons learned!

 

[E90RAW]

Unless you change from the default setting, any DJI drone will automatically RTH on loss of signal.
Almost nobody changes that default and the OP's LoS action was set to RTH.
His Mavic would have initiated RTH when he finally lost signal because the drone was flown behind an obstruction.
But his RTH height was not sufficient to clear the headland as the drone got closer.

His RTH height was set at 100 ft but RTH could only make any headway once he descended below 100 ft.
Having RTH initiate earlier in the flight while he was well above 100 ft would have only left the drone to be blown further out to sea.

If you have it set to APAS, will it clear obstacles on RTH? Or would it still hit the mountain? Or is APAS deactivated?

 

[Erik Janssen]

Maybe a strange question, but is the "speed" mode the most efficient mode to fly as far as possible with the Mavic. It may take a little longer, but what is the possible distance half power. ??????

 

[Johnmcl7]

I have tired to work my way through all of the above posts. I must admit it is way too much for my brain. The bottom line I got out of the threads was...Do not fly in strong winds. I know that it is impossible to avoid winds near the ocean. I save my flying for calm areas or I just do not fly because I am just not that good of a pilot. I have never been in Sport Mode. To me, Sport mode means risk.Not interested in speed and hope to never need sport mode for recovering my drone.

It's mentioned a couple of times but I'd highlight the advice if you're concerned about the strength of the wind then to start with fly into the head wind and see how the drone manages. If I see it's really struggling to make any progress depending on what I'm wanting, I'll either get some photos then land it or just straight up land it. On the other hand if the drone is managing fine going into the head wind I'll carry on although not let it get too far in case the wind picks up and the drone starts to struggle.

I share your caution about sports mode and rarely use it however if you haven't already, I'd spend a little time practicing with it in case you do ever need it.

 

[Meta4]

Maybe a strange question, but is the "speed" mode the most efficient mode to fly as far as possible with the Mavic. It may take a little longer, but what is the possible distance half power. ??????

In still air, Sport Mode is not the most economical mode.
It burns the battery faster and you cover less distance than at full speed in P-GPS mode.